I do not know of any credible evidence that suggests Dr Zavos can clone a human being. This seems to be yet another one of his claims to get repeated publicity.

It's extraordinary to think that if you walked into a room and said you had never heard of Hamlet, you would be regarded as a Philistine. But you could walk into the same room and say, 'I don't know what a proton is,' and people would just laugh and say, 'Why should you know?'

I think it's important for scientists to be a bit less arrogant, a bit more humble, recognising we are capable of making mistakes and being fallacious - which is increasingly serious in a society where our work may have unpredictable consequences.

Women of child-bearing age steadily run out of eggs by the continuous process of cell death. While reading a copy of the Guardian carefully from cover to cover, a normal woman will have lost on average two eggs - while, typically, a normal man will have made 70,000 new sperm.

You can't be judgmental about babies. They are all have different needs. I was left with an enduring hatred of cheese because it was forced down me when I was young.

Having a child is arguably the most important thing you do in life.

Carbon dioxide is unusual because it doesn't go through the usual three phases of matter, from solid to liquid to gas, but it goes straight from solid to gas. The volume of the gas is much greater than the volume of the solid. When a solid turns into a gas, we say it sublimes. The process is sublimation.